Ask An Expert: Photoshop Unsharp Mask Vs. Lightroom’s Sharpening Tool

Today’s “Ask An Expert” question is an outstanding one.  I’d never given much thought to the difference in sharpening an image using unsharp mask in Photoshop vs. using the sharpening tool in Lightroom.  Apparently Nat Coalson hasn’t only given it a lot of thought, he’s developed some really solid logic behind why you should use Lightroom to sharpen your images.  Nat is an Adobe Certified Expert and the author of Lightroom 2: Streamlining Your Digital Photography Process.  He’s also co-leading our “Wildflowers and Reflections in the Tetons” workshop June 10 – 13, 2010.  Here’s the question I received and Nat’s thorough response.

The Question:

How does the sharpening in Adobe Lightroom compare to unsharp mask sharpening in PhotoShop. I have heard several people claim it is good to use for capture sharpening for images submitted to agencies that will be licensed by clients who will then resize and do additional output sharpening.

What is the difference in Lightroom sharpening and Unsharp mask??

Nat Coalson Responds:

The sharpening on Lightroom’s detail panel is very different from Photoshop’s Unsharp Mask.

Unsharp Mask was developed many years ago in the early days of digital imaging. Though it has been the de facto standard on which many other methods of sharpening are based, it’s crude in comparison to newer algorithms, and can produce destructive artifacts relatively easily.

On the other hand, Lightroom’s sharpening is designed to be “gentler” in it’s application, and will produce fewer haloes and other artifacts if used properly.

Modern sharpening workflows involve several steps of sharpening, unlike older techniques of the past, when it was believed that the optimal amount of sharpening could (and should) be done in a single pass.  These days, sharpening is broken down into three stages: capture, creative and output.

Capture sharpening overcomes the loss of sharpness resulting from the pixel grid itself. Every digital image capture suffers from some amount of softening as a result of the real, organic world being mapped to a discrete grid of pixels. The sharpening on the Detail panel is intended to be capture sharpening only and to simply overcome this inherent loss of sharpness.

Creative sharpening is used to enhance specific areas of the image.  Lightroom’s local adjustment brush provides the ability to “paint” on sharpening in localized areas.

Finally, output sharpening is applied when the file is Exported or printed. Output sharpening is applied using the appropriate method and strength for the inteded output destination. For example, if you’re printing to a matte fine art paper, you would apply more sharpening than if printing to a glossy coated paper.

My default settings for sharpening on the Detail panel:

Amount 60 > The strength of the sharpening to be applied.

Radius 1.1 > The width of the sharpening along the “edges” of contrast. For images with lots of fine detail, I might go down to .8 pixel radius, and increase the Amount. Images that don’t have lots of fine detail might go up to 2.0 radius, but never more than that.

Detail 50 > Similar to radius, if the photo has lots of fine detail, use higher levels of Detail.

Masking 15 > Masking restricts the application of sharpening from being applied to areas of smooth, solid color and limited contrast. For example, blue sky or the skin in a portrait usually should not be sharpened; masking keeps the sharpening from being applied to these areas.

For all the controls, holding the option or alt key while moving the slider will show you a grayscale preview of the effect being applied.

To see the sharpening previews on the image itself, you need to be zoomed in to 1:1 or greater.

I usually fine tune these settings on an image by image basis, but these settings will give me close to the ideal amount of sharpening to begin my processing, on the majority of images.

I often apply standard or high levels of output sharpening, too.  Though there’s not a lot of direct control over this in Lightroom, the levels of output sharpening they’ve included work pretty well, and are very simple to apply.

All of this is based on raw capture; if you shoot JPG then some sharpening is already applied in the camera, and the settings would be different. (But in the Lightroom workflow, there is no reason to ever shoot JPG!)

If you do as much of your work as possible in Lightroom, you may find that you never need to go into Photoshop, especially for sharpening.  Though there will be special cases and images that need the pixel-level editing that Photoshop provides, using Lightroom’s sharpening options properly may be all you need.

Share your techniques for sharpening in Lightroom and/or Photoshop in the comments below.  Someone just might learn something and that’ll send good karma your way.  We can all use a little extra good karma!